1012] on The Road: Past, Presmf and Fnfnrc. 341 



though solid to look at, really in a liquid though viscous state. 

 They will flow, but slowly. Their surface if pressed down will yield, 

 but in time will resume its level, and solid bodies, if of lighter specific 

 gravity, placed at the bottom of a vessel containing such a substance 

 will, though not disturbed, float up to the top. A material to be 

 used for an elastic carpet for the road crust must have this viscous 

 liquid quality. Research has been made with pitch and with bitumen, 

 and the conclusion has been reached that pitch will not give satis- 

 factory I'esults, but bitumen will do so. Here is a stick of pitchy 

 material, and you can see that it has very little resiliency when sub- 

 jected to strain. Here is a bitumen stick of the same size, and you 

 will observe that it is capable of being twisted without fracture and 

 when freed slowly resumes its shape. 



It is expected that with such material laid on the top of the main 

 road crust and integrated with it a valuable road protection will be 

 supplied, so that the road crust will be practically permanent, the 

 upper protecting sheet being re-made up and re-laid as required. 



Time will not permit that I should go into detail in this matter, 

 and in any view it is still in degree in the experimental stage ; but let 

 me indicate how such a protective film will operate. We know that 

 if a wooden floor be left bare, then persons going over it will cause 

 much noise, and if nailed boots are used will more rapidly affect the 

 surface than if felt shoes were worn. As regards the noise, which is 

 the thing most thought of, it is of course a fact that it is only an 

 effect of the motion of the floor caused by shock as it is struck by 

 the successive blows of the feet coming down upon it. Let a person 

 slide over it without raising the feet and there will be little or no 

 noise. But the blows of the feet make the whole floor shake, and the 

 vibration causes the noise. It is by preventing the vibration that 

 we prevent the noise, so we put carpets or kamptulicon or oil-cloth over 

 it. The blows fall just the same, but the covering, yielding and ab- 

 sorbing the effect of the blow, prevents the floor from vibrating under 

 shock, and so the annoyance of noise is cured. It is the same in the 

 case of the road. The horse strikes a blow on the ground at every 

 pace, and the vehicle going over the unevennesses of the road also 

 strikes blows at every turn of the wheels. This operates do^vnwards 

 on the road and upwards on the passenger in the vehicle. The road 

 as we have it suffers from these blows from the stones being caused 

 to move and to lose their sharpness and become loosened in their 

 hold. It is astonishing to find how far in a macadam road the 

 effects of the blows administered to the surface go down. Here are 

 some stones taken out of a macadam road on which there is heavy 

 traffic. They were taken out at a depth of 5 inches below the 

 surface. They show the direct action at that distance down of the 

 blows delivered by the traffic. They have been so knocked about 

 that all their holding surfaces are gone, and they can no longer cHng 

 together properly to make a firm road. 



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